Tetrahydrophthalic acid compounds



Patented Mar. 17, 1953 TETRAHYDROPHTHALIC ACID COMPOUNDS Harry de V. Finch, El Cerrito, and Seaver A. Ballard, Orinda, Calif., assignors to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application March 20, 1948, Serial No. 16,148

9 Claims. (Cl. 260-346.6)

- This invention relates to cyclic compounds and to a method for their production. More particularly, the invention pertains to certain novel cyclic compounds which comprise the 3-acyloxy- 1,2,3,6-tetrahydrophthalic acid anhydrides, and to a method for their production which comprises reacting an open-chain, doubly unsaturated ester with a maleic anhydride, thereby forming a 3-acyloxy-1,2,3,6-tetrahydrophthalic acid anhydride. The invention further relates to the products which may be obtained by hydrolysis of the said phthalic acid anhydride and to a method for their production which comprises reacting the said phthalic acid anhydride with a suitable hydrolytic reagent.

This application is a continuation-in-part of our application No. 554,862, filed September 19, 1944, now abandoned.

, The novel 3-acyl0xy-1,2,3,6-tetrahydrophthalic acid anhydrides of the invention comprise the compounds of the general formula:

cyclo-alkyl and cyclo-alkenyl radicals. Ex-' amples of the hydrocarbon radicals which R1 may represent are the straight and branchchained alkyl radicals, such as methyl, ethyl, isopropyl, butyl, tert-butyl, pentyl, 2,3-diethylpentyl, heptyl, 2,4-dibutyl-octyl, decyl, dodecyl, 4,6,8-triethy1dodecyl, tetradecyl, pentadecyl, 3- butyl-fi-hexylhexadecyl. and the like; the

straight and branch-chained alkenyl radicals, such as isopropenyl, Z-butenyl, 2,5-diethyl-4- hexenyl, octenyl, 2-butyl-6-heptenyl, 2-ethyl-6- heptenyl, 2-ethyl-5-pentyl-4-decenyl, 5-dodecenyl, pentadecenyl, and the like; the saturated and unsaturated cyclic radicals, such as cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexenyl, 2-buty1-3-cyc1opentyl, 2,5-diethylcyclohexyl, 2- pentyll-cyclohexenyl, and the like; aromatic radicals, such as phenyl, tolyl, 3,5-dimethy1- phenyl, and the like.

The substituted hydrocarbon radicals which R1 may represent in the above-described general formula are the same as those hydrocarbon radicals described above for R1 wherein at least one of the hydrogen atoms on the hydrocarbon radical has been replaced by a non-interfering inorganic element or radical, or by an organic radical.

the hydroxyl group, ether, esters and ketone groups. and branch-chained alkyl radicals, such as 2- chlorobutyl, 3-acetoxy-4-ethy1hexyl, 5-hydroxyoctyl, 3-bromo-5,5-diethyldecyl, and the like; thev substituted straight and branch-chained 'alkenyl radicals, such as 3-bromo-3-butenyl, 4-butoxy-.

prising the hydrogen atom, a halogen atom,

a R radical, a 'OR radical and a radical (wherein R is an alkyl hydrocarbon).

The alkyl hydrocarbons which R may repre-p sent in the above-described group of non-interfering substituents (R2) may be any of the straight or branch-chain alkyl radicals, such as y t y i pyh. bu yl ..3-diethy p n y Such non-interfering radicals or ele-, ments may be exemplified by the halogen atoms,

Examples of the substituted straight 3 2,4,6-tributyloctyl, decyl dodecyl, pentadecyl, nonadecyl and the like.

The preferred non-interfering substituents which R2 may represent in Formula I may be exemplified by the following: as halogen atoms, bromine, and chlorine; as alkyl radicals, methyl, ethyl, butyl, tert-butyl, 2,3-diethylpentyl, dodecyl, nonadecyl and 4,6-dipentylpentadecyl radicals; as -OR radicals, methoxy, ethoxy, tert-butoxy,

4,6-dibutyloctoxy, dodecoxy, isopropoxy, pentadecoxy, and

heptoxy radicals; and as radicals, acetyl, propionyl, butyryl, o :tanoy1,1:lecianoyl, and the like radicals.

The nomenclature used in describingthe novel 3-acyloxy-1,2,3,6-tetrahydrophthalic acid anhydrides throughout the specification and appended claims may be illustrated by the following example:

(3-acetoxy-3;5-dimethyl-1,2,3,6-tetrahydrophthalic acid anhydride) 1-ethoxy-3-heptanoxy-1,2;3,6 tetrahydrophtha1ic acid anhydride 1,2.iditert butyl"- 2 (2,4' hexadi'enoxy) 1,236-tetrahydrophthalic acid anhydride] I droplithalic acid anhydride 3 (2' acetoxy 4' octenoxy) 41- (4methyloctyl) -1,2;3,6-tetrahydrophthalic acid anhydride 1 ('e'thylpentyl) 3 cyclohexenoxy 1,2,31,6-

tetrahydrophthalic acid anhydride 1,4 didodecyl 3 (2'chlorotoluoxy) 1,2,35-

tetrahydrophthalic acid anhydride 3 octenoxy 4,5 dihydroxy 1,2,3,6 tetrahydro'phthalic acid anhydride 3- dodecenoxy 4 chloro- 1,2,3,6 tetrahydrophthalic acid anhydride 3"- cyclop'entenoxy 4,5 dipropionylv- 1,'2,3,6-

tetrahydrophthalic acid anhydride 3 (Z'pentoxybenzoxy) 5 pentadecyl 1,2,3,6-

tetrahydrophthalic acid anhydride 3 (2',5,8" tetradecatrienoxy) 5 octadecyl- Y 1,2;3;6 tetrahydrophthalic acid anhydride 3-'-' (2 chloro 3' cyclohexenoxy) 3,5' di- (2" butylhexyl) -1,2,3,6-tetrahydrophthalic acid anhydride drophthalicacidanhydride- 1 octyl 4 dodecyl 3 decenoxy 1,23,6-

tetrahydrophthalic acid anhydride 1 ethyl 4 (2,5 dibromooctenyl) 3 (2"octenoxy)-1,2,3,6-tetrahydrophthalic acid anhydride 3 (2phenylbenzoxy) 4,5 ditetradecyl-1,2,3,6-

tetrahydrophthalic acid anhydride 3 (2'pheny1cyclohexyl) 6 isopropyl-1,2,3,6-

tetrahydrophthalic acid anhydride A preferred group of the 3-acy1oxy-1,2,3,6-tetrahydrophthalic acid anhydrides are those of the above described general Formula I wherein R1 represents a hydrocarbon radical containing from 1.to 7 carbon atoms and each R2 is a member of the group comprising a hydrogen atom and an alkyl radical containing from 1 to 10 carbon atoms.

These preferred 3-acyloxy-1,2,3,6-tetrahydrophthalic acid anhydrides may be represented by the following compounds:

1 pentyl 3 acetoxy 1,2,3,6 tetrahydrophthalic acid anhydride 1,2'- dibutyl 3 hexanoxy 1,2,3,6 tetrahydrophthalic acid anhydride 3 benzoxy 4,5 dodecyl 1,2;3,6:- tetrahydrophthalic acid anhydride 3 cyclohexanoxy 3,4,5 tritert butyl 1,'2,3',6-"

tetrahydrophthalic acid anhydride rahydrophthalic acid'anhydride 3 toluoxy 3,6 dioctyl ras-fit-tetrahydro phthalic acid anhydride 3 cyclopentenoxy- 4,5 dihexyl 1,2,3,6-'- tatrahydrophthalic acid anhydride 3 (2'ethyl 3 cyclohexenoxy) --3,5 -'di (2 ,'5' di=" ethylhexyl) -1,2,3,6tetrahydrophthalidacidian hydride 1 octyl 3 decyl 3 --'hepten0xy --1,'2,3,6 tetrahydrophthalic acidanhydride 1 ethyl 4 (2,5 dimethyloctyl) 3- (2hexenoxy)1,2,3,6-tetrahydrophthalic acid anhy dride 1 heptyl 3 heptanoxy"- 1,2,3,6 tetrahyd-rophthalic acid anhydride- A particularly valuable species of this preferred group of 3 acyloxy 1,2,3,6 tetrahydrophthalic' resented by the following examples 3 butyl 3 acetoxy 12,3 3 ttrahydrophthalic acidanhydride 3 pentyl- 3 (2' hexenoXy) 12135354 tetrahydrophthalic acid anhydride tetrahydrophthalioacidanh drid 1 3 heptyl 3 cyclohex'anox drophthalic-acid anhydride" 7 3 decyl 3 acetoxy 5 -tert i.-, butyl 1,2,3,6;- 1 tetrahydrophthalic acid anhydride 3 isopropyl 3 propionoxy 5 1,2,3,6-terterahydrophthalic acideanhydride 3 heptyl 3 benzoxy 5,6 dimethyl 1,23

3 hexyl 3 toluoxy 6,5 diheptyl 1,2,3-,6-"

tetrahydrophthalicacid anhydride tert bum:-

The above-described novel 3-acyloxy-1,2,3.6-'

This type of condensation reaction may be carried out by contacting approximately equivalent amounts of the maleic anhydride and the open-chain doubly unsaturated ester at a temperature sufficiently high to eifect the condensation within a reasonable time. In most instances, reaction temperatures of from about 30 C. to about 100 C. are suitable. Preferred temperatures are around 50 C.

The condensation reaction may, if desired, be carried out in the presence of a suitable solvent such as an aromatic hydrocarbon solvent, e. g. benzene or toluene. When the reaction is complete, the solvent, if any is present, may be removed and the adduct separated by crystallization or, in the case of the lower members of the series, by fractional distillation, preferably under diminished pressure.

The term maleic anhydride as used throughout the specification and claims is meant to include maleic anhydride and the substituted maleic anhydrides. The substituted maleic anhydrides comprise those maleic anhydrides wherein at least one of the hydrogen atoms joined to the carbon atoms containing the olefinic linkage of the maleic anhydride molecule is replaced by a non-interfering substituent. The substituents joined to the olefinic carbon atoms in the maleic anhydride molecule will determine the substituents to be attached to the Nos. 1 and 2 carbon atoms of novel 3-acyloxy-1,2,3,6-tetrahydrophthalic acid anhydrides of the invention and they, therefore, will be represented by the same components described above for the R2 of the general formula (I). As stated above the preferred non-interfering substituents are the members of the group comprising the hydrogen atom, a halogen atom, a -R radical, a OR radical and a radical (wherein R is an alkyl hydrocarbon as set forth hereinabove).

Examples of the substituted maleic anhydrides which may be utilized in the reaction are methyl maleic anhydride, dibutyl maleic anhydride, methyl pentyl maleic anhydride, dichloro maleic anhydride, dibutoxy maleic anhydride, ditertbutyl maleic anhydride, diacetyl maleic anhydride. didecanoyl maleic anhydride, heptoxy' maleic anhydride, heptyl chloro maleic anhydride and the like.

The maleic anhydrides to be employed for the production of the preferred group of tetrahydrophthalic acid anhydrides are the members of the group comprising maleic anhydride and the substituted maleic anhydrides wherein at least one of the hydrogen atoms joined to the carbon atoms bearing the olefinic linkage has been replaced by an alkyl group containing from 1 to 10 carbon atoms.

The open-chain, unsaturated esters possessing the conjugated system of double bonds which may be utilized in the reaction to condense with the maleic anhydride to form the novel tetrahydrophthalic acid anhydrides may be represented by the general formula:

wherein R1 is an organic radical derived from an organic acid and each R3 is a. non-interfering substituent. The R1 in the above formula of the unsaturated ester will determine the R1 to be attached to the ester group on the number 3 carbon atom of the novel 3-acyloXy-1,2,3,6-tetrahydrophthalic acid anhydrides so it, therefore, will be represented by the same substituents as described above for the R1 of the Formula I. The Rss in the above formula will determine the R2S to be attached to the number 3 to 6 carbon atoms of the novel B-acyloxy-l,2,3,6-tetrahydrophthalic acid anhydrides and they will be represented by the same substituents as described above for the Rzs of the Formula 1.

Examples of the open-chain unsaturated esters which may be utilized in the process are: l-propionoxy 1,3-butadiene, l-benzoxy 2,3-dibuty1 1,3- butadiene, 2-hexenoxy 5-acetyl 2,4-heptadiene, 3-cyclohexenoxy 4,5-dichloro 3,5-octadiene, 4- ;:iclopentenoxy 5-octyl 4,6-decadiene, and the The open-chain, unsaturated esters to be employed for the production of the preferred group of tetrahydrophthalic acid anhydrides are those members of the above-described formula wherein R1 is a hydrocarbon radical containing from 1 to '7 carbon atoms and each R3 is a member of the group comprising a hydrogen atom and an alkyl radical containing from 1 to 10 carbon atoms.

The open-chain, unsaturated esters to be employed for the production of the particularly valuable species of the tetrahydrophthalic acid anhydrides are those members of the above-described formula wherein R1 is a hydrocarbon radical containing from 1 to 7 carbon atoms, the R3 on the No. 1 carbon atom is an alkyl radical containing from 1 to 10 carbon atoms, the R3 on the No. 2 and. 4 carbon atoms are hydrogen atoms and the R3 on the No. 3 and the remaining R3 on the No. 4 carbon atom are members of the group comprising a hydrogen atom and an alkyl radical containing from 1 to 10 carbon atoms.

The above-described open-chain, doubly unsaturated esters may be prepared by any suitable method. A preferred method for preparing a particular group of the unsaturated esters is by reacting a ketone with an alpha, beta-unsaturated ketone which is capable of existing in an enol form. The reactions which take place in this methodof preparation may be illustrated be- A" variety of alpha;beta-uns'aturated' ketones mayb'e'used' asstarting materials for the "abovedescribed synthesis. Suitableketones comprise" in general those wherein the double bond is be tween the carbon atoms which are in the alpha and beta positions relative to the carbonyl group and wherein there is-alsosubstituted upon one of the alpha carbon atoms a hydrogen atom which is capable ofmigratingto theoxygen'atom ofthesaid carbonyl group, thereby forming'th'e enol form of the ketone. It has been observed that before" such astructural shift will .readily' occ'un'itis desirable that the 'twoalpha carbon atoms bearing a'totaliof a'tleast three hydrogen atoms; Suitable"alpha,beta unsaturatedketones are, therefore, mesityl oxide. 4-octen-3-one', 4- methyl': 3-hexeni-2=one, t-butyl 3-hexen 2-one, 4-*tert=butyl '3-octen-2-one, 'G-heXeyl-S-"decen-Q- one,j"6"-isooctyl '5"-decenl one l-chloro 3-octen 2'-one',' 4-acetoxy' 3-dodecen-2-one, -bromo-V methyloxy 3--0Cteh"2-0ne,' 7-heptyl '6-dodecen-5- one, 4-isopropyl 'T-hydroxy 3-o'cten'2-one, S-tertbutyl 5-decen-4-one, 4=-tert-butyl' 3-hexen-2 one, 4=propionoxy 3-penten-'2-one, 6-chloro 5-decen- 4 one', 4'-(2,5',6'triethyloctyl) 3-hepten-2-one, d-heptanoxy 5-dodecen-4-one, -bromo-B-hexene-Z-one, i-butoxy 3-hepten-2-one and the like},

Substituted ketenes ma be used in place of ketene itself. Examples of such substituted ketenes are ethyl ketene, dibutyl ketene, pentenyl ketene, phenyl ketene, cycloh'exyl ketene, cyclopentenyl ketene',-tolyl ketene, butenyl ketene, and the like;

The reaction between the .enol form" and the ketenesmay usually be effected by simply contacting the reactants at a reaction temperature and in the presence of a catalytic substance,

Suitable catalytic substances for use in the synthesis comprise such acids as sulfuric "acid, phosphoric acid, and the like; These may be employed in"1'elatively small amounts, 1. e. in amounts of about 1 or less, based on the amount of ketene 'used.

The reaction temperature to be used'is de-' termined by the nature of the ketone and keten'e used'asstarting materials. In most cases, however; reaction temperatures of' between about 50 C; and about 100 0., preferably about 75 0. maybe used. I lighertemperaturesmay be employed in certain cases, however, as' where the-reaction is carried out at superatmospherio pressure.

' Although the synthesis may usually be satisfa'ctorily carried out at atmosphereic pressure, it maybe desirable or necessary in certain cases to effect the combination of the ketene and the alpha,beta-unsaturated ketone at superatmospheric pressures, i. e; pressures of up to about 1000 pt's. i. I

It'usually suflice's to "contact" the alpha-beta:

unsaturated ketone and the k'etene in" the presence of an acid :catalyst "without the introduction I of another component into the reaction mixture.

If desired, howevenasuitable solvent-or diluent material suchfas a hydrocarbon solvent may-be admixed'with the reacta'ntsinany; desired ratio.

Use 'of such a isolvent or diluent material may "be" desirable; for- -example when ketones of rela'-- tively. *high 'molecularweightand viscous nature are being used;

The reaction timedsliKeWi'se'yariable dependare usually sufficient to effect substantial conversions of the reactantsto the desired unsaturated ester. When the reaction is complete the unsaturated ester product may be separated from unreacted starting materials as well as from any by-products which may be present by -any suitable manner, as by fractional distillation. It may be necessary in the case of highboiling products to carry out this distillation step under redu'cedv pressures, for example, at a pressure of between about 2 mm. and about 10 mm.

In the case-of certain alpha,beta-unsaturated ketones, i. e. in the case of those ketones which enolizecomp'aratively readily, it "may be possible to carry outwthereaction in acontinuous manner: This maybe done, for example,-by continuously contacting a quantity-of an alpha,beta-- unsaturatedketone and keten'e with anacid condensing agent at a suitably elevated tem perature, continuously separating the unsaturated ester product from theunreacted 'ketone,

and recycling the latter into furthercontact with a-ketene and an acid condensing agent;

A preferred procedure for preparing the novel compounds of the invention'may be illustrated. by the followingmethod showing the productionof 3,5 dimethyl 3 acetoxyl,2,3,6 tetrahy drophthalic acid anhydride" from mesityl oxide and ketene. ment gaseous ketene prepared, for example, from acetone in a standard 'ketene'generator may bepassed into a quantity of mesityl oxidewhich contains a: trace of sulfuric acid at a temperature of about C. After a. reaction time of about 3 hours theproduct may be fraction'ally distilled under reduced pressure to separate thel-methyl-1,3-pentadiene-2-ol acetate: The ester" prepared in this fashion may'then be mixed with an approximately equivalent amount of maleic anhydride and the mixture maintained at' areaction' temperature of f about 50 C. for about one-half hour. During this time the white crystalline adduct separates as a solid andmay be filtered ofi, purified and dried.

As set forth 'hereinabove the present" invemtion alsoemb'race's within its scope the products" resulting from the-hydrolysis of'the-above-described novel 3 acyloxy 1,2,3,6 tetrahydrophthalic acid anhydride;

of this type, at least three different hydrolytic products may be formed by the hydrolysis of the novel acid anhydrides, the types of hydrolytic product formed being dependent upon the char-- acter of the hydrolytic reagent employed and the conditions of hydrolysis, especially the time of contact with the hydrolytic reagent and the temperature of the reaction.

In accordance with this embodi As is apparent from a' consideration of the structure of the compounds 9 1,2,3,6-tetrahydrophthalic acids. This group of compounds may be represented by the following general formula:

R2 R2 wherein R1 is an organic radical derived from an organic acid and each R2 is a non-interfering substituent e. ga hydrogen atom, an alkyl radical, a halogen atom and the like.

As these novel 3-acyloxy-1,2,3,6-tetrahydro phthalic acids are to be derived directly from the novel tetrahydrophthalic acid anhydrides the substituents assigned to R1 and R2 of the above formula will be the same as described above for the R1 and R2 of formula (I) above, i. e. the preferred organic radicals to be represented by R1 will be the hydrocarbon radicals and substituted hydrocarbon radicals and the preferred noninterfering substituents to be represented by R2 will be the members of the group comprising the hydrogen atom, a halogen atom R radical, 9. OR radical, and a radical (wherein R is an alkyl hydrocarbon) Examples of the novel 3-acyloXy-1,2,3,6-tetrahydrophthalic acids of the invention are:

I 3 octenoxy 4,5 didecyl 1,2,3,6 tetrahydrophthalic acid The preferred group of the novel 3-acyloxy- 1,2,3,6-tetrahydrophthalic acids will be those derived from the preferred group of the novel 3- acyloxy-1,2,3,6-tetrahydrophthalic acid anhydrides, i. e. those wherein R1 is a hydrocarbon radical containing from 1 to '7 carbon atoms and each R2 is a member of the group comprising a hydrogen atom an alkyl radical containing from 1 to carbon atoms.

Examples of the preferred group of 3-acyloxy- 1,2,3,6-tetrahydrophthalic acids are:

1 pentyl-3-acetoXy 1,2,3,6 tetrahydrophthalic acid 3-benzoxy-4,5-didecyl-1,-2,3,6-tetrahydro-phthalic Iacid 3 cyclohexanoxy-2,3,5-tritert-butyl-1,2,3,6- tetrahydrophthalic acid 1 ethyl 3 (2',4'- hexadienoxy) l,2,3,6 tetrahydrophthalic acid 3-toluoxy-3,6dioctyl-1,2,3;6-tetrahydro-phthalic acid A particularly valuable species of th abovedescribed tetnahydrophthalic acids are those de- "rived from the novel 3-acyloxy-1,2,3,6-tetrahydrophthalic acid anhydrides wherein R1 is a hydrocarbon radical containing from 1 to 7 carbon atoms, the Rzs on the No. 1, 2 and 4 carbon atoms are hydrogen atoms, the R2 on the No. 3 carbon atom is an alkyl radical containing from 1 to 10 carbon atoms, and the remaining Rzs are members of the group comprising a hydrogen atom, and an alkyl radical containing from 1 to 10 carbon atoms.

Examples of this particularly valuable species of the tetrahydrophthalic acids are:

3-buty1 3 acetoxy l,2,3,6 tetrahydrophthalic acid 3 pentyl 3 (2-hexenoxy) -1,2,3,6-tetrahydrophthalic acid 3-heptyl-3-benzoxy-5,6-dimethyl-1,2,3,6-tetrahy- I drophthalic acid 3 heptyl 3 cycloheXen-oxy-1,2,3,6-tetrahydro .phthalic acid The above-described 3-acyloxy-1,2,3,6-tetrahydrophthalic acids are produced by treating .the corresponding 3 acyloxy 1,2,3,6 tetrahydrophthalic acid anhydride to hydrolysis which is sufiiciently mild to effect the conversion of the anhydride group to two carboxylic acid groupings without effecting the hydrolysis of the ester group substituted upon the number 3 carbon atom or any of the other substituents, such as the -OR and radicals which may be substituted on the ring carbon atoms. The hydrolysis may in some cases be carried out, for example, using water alone or weak aqueous solutions of acids or of bases such as sodium carbonate, potassium hydroxide, potassium carbonate, etc., using very short reaction times, e. g., reaction timesof less than about 15 minutes at room temperature or temperatures which are but slightly in excess of room temperature, i. e. temperatures of about30 C. to C. The dicarboxylic acid product may be separated from the hydrolytic mixture by any suitable means as by crystallization of either the free acid or of its metal salt, e. g. its sodium salt.

The second group of hydrolytic pro-ducts to be derived from the novel 3-acyloXy-l,2,3,6-tetrahydrophthalic acid anhydrides are the 3-hydroxy- 1,2,3,6-tetrahydrophthalic acids. compounds may be represented by the following general formula:

(III) H OH wherein R2 represents a non-interfering substituent, e. g. a hydrogen atom, an alkyl radical, a halogen atom, and the like.

As these novel 3-hydroxy1,2,3,6tetrahydrophthalic acids are to be derived directly from the novel tetrahydro-phthalic acidanhydrides or the novel tetr-ahydrophthalic acids the substituents assigned to R2 of the above-described formula will be the same as described above for the R2 of the Formula I and Formula II, i. e. the preferred substituents to be represented by R2 will be the This group of radical wherein: R is :drophthalic.- acid ..ra-dica and a edit an .alkyl hydrocarbon) Examples of the novel. 3-hydroxy-1,2,3,-6:tetra- ,hydrophthalic: acids of the inventionare:

1 butyl-3-hydroxy 1,2,3,6 tetrahydrophthalic acid 12 dihexyl 3 hydroxy 1,2,3,6-=tetrahydropht a a "3hydroxy -4,5"' diheptoxy -'1,2,-3,6 tetrah-y-dro phthalic acid 3-1hydroxy"-'5 propionoxy- 1,2;31) --tetrahydro 5 phthalic acid 1,2-dichloro-3whydroxy-11253.6 tetrahydrophthalic acid The preferred group of the novel 3-hydroxy- 1,2,3,fiwtetrahydrophthalic acids will be ,those de- 7 V. d f rom-the preferred group, of "the novel ,3-

l-pentyl 3 hydroxy-1,2,3,6-tetrahydrophthalic acid 3hydroxy-4,5-didecy1-,1,2,3,6-tetrahydrophthalic acid 12 hy xy 4i5 '-'-;diisQpr0py1-1 ,2,-3',6-;-tetrahydro- ,-phthalic acid hydroxy 5 I2n y 1;2,'3,6-tetrahy-drophthalic acid - ydroxy 4 tert.-,- butyl -;1,2,-3;6 tetrahyparticularly valuable species of ,the'abovedescribed 3-hydroxy-1,2,3,6 tetrahydrophthalic acidsarethose. derived from the novel 31acyloxy- 1 2,3,6etetrahydrophthalic acid anhydrides ,or

s. acids (wherein the Rzs on the No. -1, 2an d .4rcar- .bon:atoms-2ame hydrogen atoms, the R2 on: the No.

3carbonaatom. is an alkyl radical containing; from ,lo arbonatoms, and the. remainingRzare ,pnembers of the'grcup comprising a hydrogen atom, and .an alkyl-radical containing fromvl ito lil -carbon atoms.

'rExa'mples of this; ;particuIarly valuableppecies of the 3-hydroxy-1,2,3,6-tetrahydrophthalic acids are:

XII-"he? above-described 3 hydroxy-l,2,3,6-tetra- ..hydrophthalic.- acids,-are-produced. from the corresponding a-acyloxy-1',2;3,6 tetrahydrophthalic oacidfanhydride or-acidlbytreating thesaid an- ,hydride crecid .tosomewhat more vigorous hydrolytic, conditionethan .those. described above jflfor. the production of r the acids, so that the an- .Jhydride group is hydrolyzed .to two carbcxylic groups and .thelpesterqgroupr is hydrolyzed to a tromthereaction mixture in the form of-its s-sodium salt-or intheform of" the free acidsubstantially "as described hereinabove.

A preferredprocedure forgcarrying out'thihydrolytic reaction may be illustrated by'ythe method which may bensed for the production p t hydr xy 5 y1 -.11 2;. -itetrahyd phthalic acid from '3-acetoXy-5-methyll;2,3;6- Qtetrahydrophthalic acid anhydride. :ance with this embodiment the said 3,-acetoxy- In accord- 5-methy1 1,2,3,6 tetrahydrophthalic acid, anhydride maybe mixed Witha suitable .hydrolytic reagent, e. g.,an aq ueo.us solution of sodium caribonate, containing about ,1"% .of sodium carbonateand the'resultingmixturepheatedto a temperature of about 40 C. After a reaCtiontime of about /2 hour the disodium salt of "3-hydroxy- S-methyl-1,2,3,6-tetrahydrophthalic acid may be separated from the reaction mixture or the mixture may be :neutralized :-,with ,an. acid. re. g.

.,hydrochloric-.,-acid, thereby .causing the precipitation of the desired tetrahydrophthalic acid -.;de rivative. a V

The 3 hydroxy -'1';2;3;6 tetra-hydrophthalic acids wherein there is an alkyl group substituted on the No; 3 carbon atom were notinclu'de'd in the aboveedescribed :group as their preparation is diflicult and in most cases impossible to accomplish. Thisis because the alcohols of this type i. e. a tertiary alcohol are ,rea-dilyfdehydrated --with the formationzof an olefini-c linkage. A furtheri-actor favoring such dehydrationis to be found in the fact thatthe hydroxylgroupis substituted upona carbon atom "which is ,in the beta position relative tonne of the carboxyl groups and as is Well known the,;beta-hydroxycarboxylic acids readily lose water to form unsaturated acids. 'In the case ofthe novel compcundsof the invention when'such dehydra- -tion takes place-a new double bond is formed within the ring, thereby 'fcrming a 1,2 dih-ydrophthalic "acid. --tetrahydrophthalic acidanhydrides *of the -in- .any of 'the afore-said intermediate hydrolytic products, the hydrolysis being carried out under such-conditions that the .estergroup ishydrolyzed to a free hydroxyl group, the said'free hydroxyl group is 'removedi'fromthe ring by a secondary dehydration reaction, thereby resulting in the formation of a second olefinic'linkage, and the anhydride group is hydrolyzed to 'form two carboxyl groups.

The group of -1,2-di;hydrophthalic acids. em-

' drophthalic acids are:

C-COOH CCOOH wherein R2 is a, non-interfering substituent, e. g. a hydrogen atom, an alkyl radical, a halogen atom, and the like.

As these novel 1,2-dihydrophthalic acids are to be derived directly from the novel tetrahydrop'hthali-c acid anhydrides or any of the aforesaid intermediate hydrolytic products the substituents assigned to R2 of the above-described formula may be the same as those described above for the R2 of the Formulae I, II, and III, i. e. the preferred substituents to be represented by R2 may be members of the group comprising the hydrogen atom, a halogen atom, a R radical, a -OR radical, and a o tR radical (wherein R is an alkyl hydrocarbon).

Examples of the novel 1,2-dihydrophthalic acids of the invention are:

The preferred group of the novel 1,2-dihydro- .phthalic acids of the invention will be those derived from the preferred group of the novel 3- acyloxy-l,2,3,6-tetrahydrophthalic acid anhydride and the aforesaid intermediate hydrolysis products, i. e. those wherein R2 is a member of the group comprising a hydrogen atom and an alkyl radical containing from 1 to carbon atoms.

Examples of the preferred group of 1,2-dihy- 1,2-di-h-exyl-3-decyl-1,2-dihydrophthalic acid 3-isobutyl-5-octyl-1,2-dihydrophthalic acid l-pentyl-3-hexyl-1,2-dihydrophthalic acid 3isopropyl-4,5-ditert-butyl-1,2 dihydrophthalic acid 3-pentyl-5,6-dimethyl-1,2-dihydrophthalic acid 3-octyl-3-is-opropyl-1,2,dihydrophthalic acid I 3-heptyl-5-tert.butyl-1,2-dihydrophthalic acid 3-decyl-5,6-dioctyl-1,2,-dihydrophthalic acid The above-described l,2,-dihydrophthalic acids are prepared from the 3-acyloxy-l,2,3,6-tetrahydrophthalic acid anhydrides or'acids covered by Formulae I, II, and III by treating the said anhydride or intermediate hydrolysis products to such conditions that the ester group, if present, is hydrolyzed to a hydroxyl group, the hydroxyl group is removed by dehydration and the anhydride group, if present, is hydrolyzed to two carboxyl groups. This hydrolytic process may be carried out by using any of the hydrolytic reagents mentioned hereinabove, i. e. water, aqueous solutions of bases or aqueous solutions of acids, at an elevated temperature for a reaction time which is sufliciently long to efiect the desired hydrolysis. A preferred procedure may be represented by that which may be employed to convert 3-actoxy3,5-dimethyl-l,2,3,6-tetrahydrophthalic acid anhydride to 3,5-dimethyll-2-dihydrophthalic acid. In this embodiment the 3 acetoxy 3,5 dimethyl l,2,3,6 tetrahydrophthalic acid anhydride is reacted with an excess of an aqueous solution of l N sodium hydroxide, using a solvent such as dioxane if desired. The reaction may be carried out at any suitable temperature, preferably a temperature which is substantially the boiling temperature of the hydrolytic mixture. When the hydrolysis is complete the reaction mixture is neutralized with an acid, e. g. a dilute aqueous solution of hydrochloric acid and the desired 3,5-dimethyl1,2-dihydrophthalic acid extracted with a suitable solvent such as isopropyl ether. The resulting solution of product in solvent may then be dried and evaporated in order to obtain the dihydrophthalic acid product.

To illustrate the manner in which the invention may be carried out the following examples are given. It is to be understood, however, that the examples are given for the purpose of illustration only and should not be regarded as limiting the invention in any way.

Example I Mesityl acetate was prepared by passing ketene into a quantity of mesityl oxide which contained a trace of sulfuric acid. The temperature of the reaction mixture was maintained at about C. during this addition. When the reaction was complete, 1. e. after ketene had been added for from 3 to 4 hours, the product was fractionally distilled to separate the mesityl acetate which boiled at about 58 C. at 10 mm.

About 3 parts by weight of mesityl acetate prepared in this fashion was then mixed with about 2 parts of maleic anhydride and the resulting mixture heated at about 50 C. for about 20 minutes. The white crystalline product which separated was removed by filtration and purified by washing with a solvent and drying. The

. 3 acetoxy 3,5 dimethyl 1,2,3,6 tetrahydrophthalic acid anhydride prepared in this fashion melted at 283 C. It analyzed 60.5% C. (calculated, 60.4% Equivalent weight 78 (theory '79) Example II Using the method outline in Example I, 3 methyl 3 acetoxy l,2,3,6 tetrahydrophthalic acid anhydride is prepared from methyl n-propenyl ketone, ketene, and maleic anhydride.

3 benzoxy l,2,3,6 tetrahydrophthalic acid anhydride is prepared by heating maleic anhydride with l-benzoxy-l,3-butadiene at a temperature between 50 C. and C.

In like manner are prepared the following anhydrides: l butyl 3 pentanoxy 1,23,6-

tetrahydrophthalic acid anhydrides from butyl I maleic anhydride and 1 pentanoxy 1,3 butadiene; 1,2 dihexyl 3 cyclohexanoxy 1,23,6-

3 -;octyl 3v hexen0xy ;1,2,3,6 tetrahydro- --D thalic. acidanhydride from maleic anhydride and .1 octyl +11 -,hexenoxy 1,3 butadiene;

3 octenoxy 4,5 dihydroxy- 12,3,6 tetrahyrophthalic acid from. dihydroxy'maleic anhydride and .1-'octenoxy-l ,3+butadiene; 3-phenyl- 3 heptenoxy 5 phenyL- l,2,3,6 tetrahydro-- phthalic acid. anhydride from :maleic anhydride and 1,3 dipheny1.- 1.- heptenoxy 1,3 butaydiene; "l,2.3,4.- tetraethyl 3 (2 phenylbenz oxy) v-';I,2,3,'6 tetrahydophthalic acid anhydride "from :diethyl maleic anhydride and l-ethyl-l (2fphenylbenzoxy) -'2 ethyl 1,3 butadiene;

"1 -ie thoxy 4 -'butoXy 3 isopropanoxy 1, 12,3;6.-..tetrahydrophthalic acid anhydride from ethoxy1maleic. anhydride and .1.-isopropanxy-2- "butoxy -;1,3 butadiene; didecyl---l,2,3,6-tetrahydrophthalic acid anhydride and 3 tolucxy 3,6-

from' maleic anhydride' and 1 toluoxy- 1,4-

didecyl-lfi-butadiene.

, Example'lIl fIhe-sodiumsalt. of 3acetoxy-5-methyl-1,2,3,6- tetrahydrophthalic acid is prepared from 3-ace- -toxy 5 --methyl -.1,2,3,6 tetrahydrophthalic :acid anhydride synthesized as described in Example I vby'reaction with a, hydrolytic reagent comprising .a dilute aqueous solution of sodium carbonate at atemperature of about 25 C. for a reaction time of aboutminutes. The free acid may be prepared from its sodium salt by reaction with an approximately equivalent amount of a dilute mineral acid such as hydrochloric acid.

In like manner are produced 3-toluoxy-3,6- didecyl l,2',3;6 tetrahydrophthalic acid from 3 toluoxy 3,6 didecyl 1,2,3,6 tetrahydrophthalic acid anhydride; 1.-ethoxy-4-butoxy-3- isopropanoxy 1,'2,3,6 tetrahydrophthalic acid from its corresponding anhydrides; 1,2,3,4-tetraethyl 3- (Z'phenylbenzoxy) 1,2,3,6 tetrahydrophthalic acid from itsanhydride; 3-octyl-3- hexenoxy 1,2,3,6 tetrahydrophth-alic acid from its anhydride; 1-- isopropyl 3 benzoxy 1,23,6- tetrahydrophthalic acid from its anhydride; and 1,2-- dich1oro- -3 cyclopentenoxy 1,2,3,6.-. tetra- "hydrophtnaiic acid from its anhydride.

xample 1v "hydrophthalic acid with a hydrolytic reagent comprisinga dilute aqueous sodium carbonate solution thereby forming the disodium salt of .a 3 hydroxy-l,2;3,6-tetrahydrophthalic acid, and reacting the said salt with a dilute mineral acid,

- thereby forming the desired tetrahydrophthalic acid derivative.

In like manner are, preparedxS -hydroxy-'3;6-didecyl-1,2,3,6-tetrahydrophthalic .anhydride acid 'phthalic acids of the -secticidal toxicants.

phthalic acid anhydride; 3-hydroxy- 5,6.-;dioctyl- 1,2,3,G-tetrahydrophthalic acid from 3-acetoxy- 5,6 dioctyl-l,2,3,6-tetrahydr0phthalic acid anhydride; 1,2 dihexyl-3.-hydroXy-1,2,3,6-tetrahydrop-hthalic acid from 1,2-diheXyl-3-benzoxyl,2,3,6-tetrahydrophthalic acid anhydride; and 4-phenyl-5-tert-butyl-3-hydroxy-1,2,3,6-tetrahydrophthalic acid from 3-.-cyclohexanoxy-4-phenyI-S-tert-butyl-1,2,3,6-tetrahydrophthalic acid.

Example "V 3,5-dimethyl-1,2-dihydrophtha1icacid was preared y trea -a et y-3 me h 1* 2. tetrahydrophthalic acid, prepared as in Example I, with a 1 N .aqueous sodium hydroxide solution. The hydrolytic reaction was carried outfiby dissolvingythe crude tetrahydrophthalic acidderivative in a solvent comprising .dioxanegand heating together with the IN caustic at a'reflux temperature. 'Ilie hydrolytic reaction productgwas then neutralized-With acid and extracted with a solvent to isolate the pure 3,5-dimethy1-1,-2+dihydrophthalic acid Which melted at-200 C. to 203 C. and analyzed 61.1% C, 6.13% H (theory 60.6% C, 6.15% H). Its equivalent weight was found to be .98 (theory 10 1).

In a fashion similar to that .described'above forthe preparation of 3.5-dimethyl-1,2-jdihydrophthalic acid, are prepared 3-octyl-'1,2-dihydrophthalic acid from 3-octy1-3-acetoxyl-l2,3,6- tetrahydrophthalic :acid .anhydride; 3-tert-butyl 1,2-dihydrophthalic acid from 3-tert-butyl-3- acetoxy- 1,2;3,6-tetrahydrophthalic .acid anhydride; 5-methyl-3-ethy1:1,2-dihydrophthalicacid from 3acetoXy-3-ethyl-5-methyl-1,2,3,6-tetrahydrcphthalic acid anhydride; l, 2,3,6-triinethy1-1,2- dihydrophthalic acid from 1,2,3-trimethy1-3eacetoxy-l2,3,6-tetrahydrophthalic acid anhydride; 3,4-dipentyl-1,2-dihydrophthalic acid from 3,4- dipentyl 3 acetoxy l,2;3,6-tetrahydrophthalic acid anhydride; and 3,5,6-trimethyle1,2-dihydrophthalic acid from 3,5,6-trimethyl-3-acetoxy- 1,2,3,6-tetrahydrophthalic acid anhydride.

acid and a hydroxy-substituted .tetrahydrophthalic-acid. l hese compounds are, therefore,

useful insecticides; their insecticidal. activity being due to the fact that V lyzed to liberate a free organicacid. Certain-of the esters, 'e. g. diallyl esters of' the tetrahydroinvention, are also useful in- Other esters such as theunsaturated esters are useful as resin intermediates While esters such as the dibutyl esters are useful as plasticizers,-particularly for vinyl resins and polyallyl-type resins, and also as rubber softeners andretarders. The compounds of"theinvention are extremely valuable intermediates in thesynthesis of other useful organic compounds because of the relatively large number of substituent groups which are present within-their -molecular structure.

In; addition to their use in the preparation of 'the'hereinabove describedhyin the preparation of a drolytic products 7 and they are readily hydrowide variety of esters they may be hydrogenated to form useful cyclohexene derivatives, dehydrogenated to form phthalic acid derivatives useful for a wide variety of purposes and halogenated by reaction a free halogen such as chlorine or bromine to form halogen-containing compounds which are of value, for example, as insecticides, solvents, resin intermediates, etc.

We claim as our invention:

1. 3 acetoxy-3, 5-dimethy1-l,2,3,6-tetrahydrophthalic acid anhydride.

2. 3 methyl 3 acetoxy 1,2,3,6-tetrahydrophthalic acid anhydride.

3. A process for the production of 3-acetoxy- 3,5-dimethyl-1,2,3,6-tetrahydrophthalic acid anhydride which comprises reacting mesityl acetate with an approximately equivalent amount of maleic anhydride at a temperature between about 30 C. and 100 C.

4. A process for the production of 3-acyloxy- 1,2,3,6-tetrahydrophthalic acid anhydrides which comprises condensing an open-chain doubly unsaturated ester of the formula:

R: Ra a (l) 1 R3C=CO=CR3 wherein R1 is a hydrocarbon radical and each R: is a member of the group consisting of hydrogen, halogen, alkyl radicals, --OR radicals and n cn radicals wherein R is an alkyl radical with an approximately chemical equivalent amount of a member of the group consisting of maleic anhydride and the substituted maleic anhydrides wherein at least one of the hydrogen atoms joined to the carbon atoms bearing the olefinic linkage has been rep-laced by an alkyl radical.

5. A process for the production of 3-acyloxyl,2,3,G-tetrahydrophthalic acids which comprises condensing an open-chain, doubly unsaturated ester of the formula:

wherein R1 is a hydrocarbon radical and each R3 is a member of the group consisting of hydrogen, halogen, alkyl radicals, OR radicals and 0 II on radicals wherein R. is an alkyl radical with an wherein R1 is a hydrocarbon radical, R2 is an alkyl radical and R3 is a member of the group consisting of hydrogen, halogen, alkyl radicals, OR radicals and I ER radicals wherein R is an alkyl radical, and (2) acids derived from the aforedescribed anhydrides by hydrolyzing the anhydride group.

HARRY DE V. FTNCH. SEAVER A. BALLARD.

REFERENCES CITED The following references are of record in the file of this patent:

FOREIGN PATENTS Number Country Date 739,438 Germany Sept. 28, 1943 OTHER REFERENCES Pasquinelli: Chemical Abs-tracts, vol. 38, p. 5734, (1943).

Liebigs Annalen de Chemie, vol. 551 (1942), pp. 21, 22, 23, 59 and 60. 

9. A COMPOUND OF THE GROUP CONSISTING OF (1) ANHYDRIDES OF THE FORMULA 